Audio devices are often used in noisy environments in which received signals from microphones can be degraded by background noise and interference. In particular, background noise and interference can degrade the fidelity and intelligibility of speech.
There are many speech enhancement techniques that attempt to attenuate the noise, increase signal-to-noise ratios (SNR), and improve speech perception. However, speech enhancement processing under adverse conditions is still challenging. In particular, when the SNR is low or noise is non-stationary (i.e., time-varying), the results are plagued by speech distortions and unnatural sounding or fluctuating residual background noises. Thus, many noise reduction techniques make speech sound less pleasant, although they have improved SNR.